5´-tiRNAVal作为新的乳腺癌标志物及其作用机制研究

tRF/tiRNA is a class of non-coding RNA derived from tRNA cleavage. Its contribution to breast cancer is largely unknown. By comparing our previous RNA-seq data for the transcriptomes of 6-paried breast cancer tissues and paracancerous tissues, we have identified a function-unknown 5´-tiRNAVal with significantly low expression in breast cancer tissues, serum and cells after in-deep trancriptome data analysis and sample-extended validation. Our preliminary data indicates 5´-tiRNAVal might play important role in breast cancer metastasis with following evidences: its expression level is negatively related to with TNM stage and lymphonode metastasis of breast cancer patients, cancer cells with higher metastasis potential show lower expression of 5´-tiRNAVal, and overexpression of 5´-tiRNAVal inhibits metastasis potential of breast cancer cell in vitro. Addition preliminary data raise a hypothesis that 5´-tiRNAVal represses breast cancer metastasis via targeting FZD3, leading to inactivation of wnt/β-catenin siganlling pathway. In current proposal, we will focus on the function and mechanism of 5´-tiRNAVal in breast cancer metastasis, based on pre-experimental results, to reveal its expression in cancer tissue and paracancerous tissue of patients with breast cancer, to clarify the application value of serum 5´-tiRNAVal in diagnosis, evaluation and prognosis of breast cancer, to explore its effect on biological behaviors of breast cancer cells, and to propose the molecular mechanism of 5´-tiRNAVal in regulation of FZD3 to promote malignant growth of breast cancer cells. This study will provide the evidence of 5´-tiRNAVal as a novel biomarker for breast cancer and possesses important scientific significance.

tiRNA是tRNA切割产生的小非编码RNA，在乳腺癌中鲜有报道。前期我们收集6对乳腺癌及癌旁组织，测序筛选分析和扩大样本验证，锁定一条在乳腺癌组织、血清、细胞中均显著低表达的功能未知tiRNA，即5´-tiRNAVal。预试验发现：5´-tiRNAVal与TNM分期和淋巴结转移负相关；恶性程度越高，5´-tiRNAVal表达越低；过表达5´-tiRNAVal可抑制细胞增殖迁移；预试验暗示5´-tiRNAVal通过靶向FZD3负向调控wnt/β-catenin信号通路，具有作为乳腺癌诊断标志物的潜能。本项目将在前期基础上，揭示5´-tiRNAVal在乳腺癌组织的表达规律，研究血清5´-tiRNAVal在乳腺癌诊断、疗效评估及预后判断中的应用价值，阐明5´-tiRNAVal调控FZD3促进乳腺癌恶性生长的分子机制，为5´-tiRNAVal作为乳腺癌标志物提供依据，具有重要的科学意义。

研究血清5´-tiRNAVal在乳腺癌诊断、疗效评估及预后判断中的应用价值，探讨它对乳腺癌细胞生物学行为的影响，并阐明5´-tiRNAVal调控FZD3促进乳腺癌细胞恶性生长的分子机制。具体内容如下：.1．乳腺癌患者血清5´-tiRNAVal的诊断和预后价值研究.分析5´-tiRNAVal水平与传统乳腺癌诊断指标如血清CEA、CA153等指标间相关性，建立血清5´-tiRNAVal诊断乳腺癌的ROC 曲线，对5´-tiRNAVal进行临床诊断性能评价。.分析评价血清5´-tiRNAVal对乳腺癌的预后价值。.2. 5´-tiRNAVal在乳腺癌中的功能研究.用RT-PCR检测乳腺癌细胞株中的5´-tiRNAVal的表达水平；通过增殖实验、克隆形成实验、凋亡实验，从细胞层面、动物水平评价5´-tiRNAVal对乳腺癌恶性进展的影响。.3. 5´-tiRNAVal负向调控FZD3的分子机制研究.研究细胞株中5´-tiRNAVal和FZD3的相关性；研究5´-tiRNAVal/FZD3/Wnt/β-catenin通路机制。.4．5´-tiRNAVal/FZD3/Wnt/β-catenin通路在组织样本中的相关性研究.从动物层面、乳腺癌患者临床特征等层面，验证5´-tiRNAVal/FZD3/Wnt/β-catenin负向调控通路在促进乳腺癌恶性进展中的相互关系。